Fixes #4450: Added `yii\bootstrap\Nav::renderDropdown()`

CHANGELOG.md

@@ -6,6 +6,7 @@ Yii Framework 2 bootstrap extension Change Log
 
 - Bug #5570: `yii\bootstrap\Tabs` would throw an exception if `content` is not set for one of its `items` (RomeroMsk)
 - Enh #4181: Added `yii\bootstrap\Modal::$headerOptions` and `yii\bootstrap\Modal::$footerOptions` (tuxoff, samdark)
+- Enh #4450: Added `yii\bootstrap\Nav::renderDropdown()` (qiangxue)
 - Enh #5735: Added `yii\bootstrap\Tabs::renderTabContent` to support manually rendering tab contents (RomeroMsk)
 - Enh #5799: `yii\bootstrap\ButtonGroup::buttons` can take all options that are supported by `yii\bootstrap\Button` (aleksanderd)
 - Chg #5874: Upgraded Twitter Bootstrap to 3.3.x (samdark)

Nav.php

@@ -171,12 +171,7 @@ class Nav extends Widget
                 if ($this->activateItems) {
                     $items = $this->isChildActive($items, $active);
                 }
-                $items = Dropdown::widget([
-                    'items' => $items,
-                    'encodeLabels' => $this->encodeLabels,
-                    'clientOptions' => false,
-                    'view' => $this->getView(),
-                ]);
+                $items = $this->renderDropdown($items);
             }
         }
 
@@ -188,6 +183,23 @@ class Nav extends Widget
     }
 
     /**
+     * Renders the given items as a dropdown.
+     * This method is called to create sub-menus.
+     * @param array $items the given items. Please refer to [[Dropdown::items]] for the array structure.
+     * @return string the rendering result.
+     * @since 2.0.1
+     */
+    protected function renderDropdown($items)
+    {
+        return Dropdown::widget([
+            'items' => $items,
+            'encodeLabels' => $this->encodeLabels,
+            'clientOptions' => false,
+            'view' => $this->getView(),
+        ]);
+    }
+
+    /**
      * Check to see if a child item is active optionally activating the parent.
      * @param array $items @see items
      * @param boolean $active should the parent be active too